Image pickup apparatus

ABSTRACT

An image pickup apparatus is provided that can switch between an optical viewfinder mode for identifying an object using an optical viewfinder and a live view mode for identifying an image of an object using a monitor. The apparatus includes an auto-focus unit able to be configured in the optical viewfinder mode; and a control unit configured to switch, in a case where a mode for performing exposure control in association with an auto-focus result obtained by the auto-focus unit is set, when the optical viewfinder mode is switched to the live view mode, to a mode for performing exposure control not in association with the auto-focus result.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to image pickup apparatuses capable ofswitching between an optical viewfinder and a live view mode.

2. Description of the Related Art

Many cameras having, besides a known optical viewfinder, an electronicviewfinder that obtains an image in an image pickup range using an imagepickup device and displays the obtained image using a liquid crystaldisplay monitor or the like (hereinafter referred to as a live viewfunction or mode) have been proposed. Features of the live view functioninclude strength against external darkness, that is, a reduction inluminance, ease of checking the depth of field, ease of performingspecial display such as enlargement, and the like.

Single-lens reflex cameras achieve focus using a phase-differenceauto-focus (AF) method of achieving focus by separating light that haspassed through an image pickup lens into components using a separatorlens and obtaining the amount of lens movement based on the distancebetween images. Most of cameras of this type having the live viewfunction use a contrast AF method of achieving focus based on contrastof image data obtained by an image pickup device.

In order to make use of features of the optical viewfinder and the liveview mode, a single-lens reflex camera that switches between the opticalviewfinder and the live view function has been proposed in JapanesePatent Laid-Open No. 5-107595.

When a camera can switch between the optical viewfinder and the liveview mode, the camera performs the phase-difference AF method when usingthe optical viewfinder and performs the contrast AF method in the liveview mode. The phase-difference AF method has an excellent focus speed.The contrast AF method has excellent focus precision. The two AF methodshave respective features. There may be a situation where a user of thecamera wants the camera to perform the phase-difference AF method evenin the live view mode. To do so, a camera that can switch between the AFmethods has been proposed in, for example, Japanese Patent Laid-Open No.2001-272593.

Single-lens reflex cameras are often required to have a snap-shootingability. Even when single-lens reflex cameras have the live viewfunction, they may not use the contrast AF method, which requires a longtime to achieve focus. In this case, focus in the live view mode isbasically achieved with manual focus. Unlike a normal operation where AFis set by the first stroke of a release button and then an image iscaptured by the second stroke of the release button, an image can becaptured without regard to a focus position. In such a case, when thephase-difference AF method is enabled by a user operation, the mode ischanged to the optical viewfinder mode for a necessary period, an AFoperation is performed using the phase-difference AF method, and thenthe mode is changed back to the live view mode.

However, in the phase-difference AF method using the optical viewfinder,some functions are in association with a photometric program using theoptical viewfinder. These functions include an automatic depth-of-fieldpriority AF function (hereinafter called “auto-depth”, which will bedescribed in detail later) and an auto-exposure (AE) lock function thatlocks a photometric value when focus is achieved based on an evaluationphotometry result at a focus ranging point. When the optical viewfinderand the live view function use different photometric methods, if themode returns to the live view mode after an AF operation using thephase-difference AF method has been performed and photometry isperformed with a photometric method in the live view mode, inconsistencymay be caused.

SUMMARY OF THE INVENTION

The present invention provides an image pickup apparatus that can avoidinconsistency in AF and a photometric method when an optical viewfinderand a live view mode are switchable from one to the other.

According to an aspect of the present invention, there is provided animage pickup apparatus that can switch between an optical viewfindermode for identifying an object using an optical viewfinder and a liveview mode for identifying an image of an object using a monitor. Theimage pickup apparatus includes an auto-focus unit able to be configuredin the optical viewfinder mode; and a control unit configured to switch,in a case where a mode for performing exposure control in associationwith an auto-focus result obtained by the auto-focus unit is set, whenthe optical viewfinder mode is switched to the live view mode, to a modefor performing exposure control not in association with the auto-focusresult.

According to the aspect of the present invention, it is possible toprovide an image pickup apparatus that can avoid inconsistency in AF anda photometric method when an optical viewfinder and a live view mode areswitchable from one to the other.

Moreover other embodiments, features, and aspects of the presentinvention will become more apparent from the following detaileddescription taken in association with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example image pickup apparatus accordingto an embodiment of the present invention.

FIG. 2 is a flowchart of an example operation in a normal photographingmode according to the embodiment of the present invention.

FIG. 3 is a flowchart of an example operation in a live view modeaccording to the embodiment of the present invention.

FIG. 4 is a flowchart of an example phase-difference AF operation in thelive view mode according to the embodiment of the present invention.

FIG. 5 is a flowchart of an example operation in an auto-depth modeaccording to the embodiment of the present invention.

FIG. 6 is a flowchart of an example photographing-mode switchingoperation in the live view mode according to the embodiment of thepresent invention.

FIG. 7 is a flowchart of an example AF-mode switching operation in thelive view mode according to the embodiment of the present invention.

FIG. 8 is a flowchart of an example AF lock operation after focus isachieved according to the embodiment of the present invention.

FIG. 9 is a flowchart of an example operation where no AF lock operationis performed after focus is achieved according to the embodiment of thepresent invention.

DESCRIPTION OF THE EMBODIMENTS

The present invention will now be described in detail with reference tothe drawings showing preferred embodiments thereof.

FIG. 1 is a block diagram of an image pickup apparatus having a liveview mode according to an embodiment of the present invention. The imagepickup apparatus includes a main body 100 of the apparatus, recordingmedia 200 and 210, and a replaceable-type lens unit 300.

The internal structure of the main body 100 is described below. The mainbody 100 includes a shutter 12 that controls the exposure amount; animage pickup device 13 that converts an optical image formed through theshutter 12 into an electrical signal; an analog-to-digital (A/D)converter 16 that converts an analog signal from the image pickup device13 into a digital signal; and a timing generator 18 that provides aclock signal and a control signal to the image pickup device 13, the A/Dconverter 16, and a digital-to-analog (D/A) converter 26, and that iscontrolled by a memory controller 22 and a system controller 50, whichare described later.

Furthermore, the main body 100 includes an image processing unit 20 thatperforms predetermined pixel interpolation processing and colorconversion processing of data from the A/D converter 16 or data from thememory controller 22. If needed, the image processing unit 20 performspredetermined calculation processing using data of a captured image.Based on the calculation result, the system controller 50 describedlater controls a shutter controller 40 and a ranging unit 42. That is,the image processing unit 20 performs through-the-lens (TTL) AFprocessing. Furthermore, the image processing unit 20 performs AEprocessing and electronic flash (EF) processing. The image processingunit 20 also performs predetermined calculation processing using thecaptured image data and performs TTL automatic white balance (AWB)processing based on the obtained calculation result.

In the present embodiment, the ranging unit 42 and a photometer 46 areprovided as dedicated units. Therefore, the AF processing, the AEprocessing, and the EF processing may be performed using the rangingunit 42 and the photometer 46, and the AF processing, the AE processing,and the EF processing may not be performed using the image processingunit 20. Alternatively, the AF processing, the AE processing, and the EFprocessing may be performed using the ranging unit 42 and the photometer46, and additionally the AF processing, the AE processing, and the EFprocessing may be performed using the image processing unit 20. Theranging unit 42 and the photometer 46 are enabled when an opticalviewfinder 104 is used.

The main body 100 includes the memory controller 22. The memorycontroller 22 controls the A/D converter 16, the timing generator 18,the image processing unit 20, an image display memory 24, the D/Aconverter 26, a memory 30, and a compression/decompression unit 32. Dataobtained by the A/D converter 16 is written into the image displaymemory 24 or the memory 30 via the image processing unit 20 and thememory controller 22 or via the memory controller 22 but not the imageprocessing unit 20.

The main body 100 includes the image display memory 24; the D/Aconverter 26; an image display unit 28 that includes thin-filmtransistors (TFTs), a liquid crystal display (LCD), and the like andthat displays image data for display, which is written in the imagedisplay memory 24, via the D/A converter 26; and the memory 30 thatstores captured still images. The memory 30 has a sufficient storagecapacity for storing a predetermined number of still images. Therefore,even in a continuous photographing operation where multiple still imagesare consecutively captured, many images can be quickly written into thememory 30. The memory 30 may also be used as a work area for the systemcontroller 50.

The main body 100 includes the compression/decompression unit 32. Thecompression/decompression unit 32 compresses/decompresses image datausing an adaptive discrete cosine transform (ADCT) or the like. Thecompression/decompression unit 32 reads an image stored in the memory30, compresses or decompresses the image, and writes the processed datainto the memory 30.

The main body 100 includes the shutter controller 40. The shuttercontroller 40 controls the shutter 12 in association with an aperturecontroller 340 that controls an aperture 312 based on photometricinformation provided from the photometer 46. The ranging unit 42 is aranging unit for performing the AF processing. A light beam incident ona lens 310, which will be described later, is directed to enter theranging unit 42 via the aperture 312, lens mounts 306 and 106, a mirror130, and a ranging submirror (not shown) using a single-lens reflexmethod. With the ranging unit 42, a focus state of an image formed as anoptical image can be measured.

The photometer 46 is a photometer for performing the AE processing. Alight beam incident on the lens 310 is directed to enter the photometer46 via the aperture 312, the lens mounts 306 and 106, the mirror 130, amirror 132, and a photometric lens (not shown) using a single-lensreflex method. With the photometer 46, an exposure state of an imageformed as an optical image can be measured. The photometer 46 also hasthe EF processing function by operating in association with a flash 48.

The main body 100 includes the flash 48. The flash 48 has a floodlightfunction for AF auxiliary light and a flash adjusting function. AFcontrol may be performed using the measurement result obtained by theranging unit 42 and the calculation result obtained by the imageprocessing unit 20 using image data captured by the image pickup device13. Furthermore, exposure control may be performed using the measurementresult obtained by the photometer 46 and the calculation result obtainedby the image processing unit 20 using the image data captured by theimage pickup device 13.

The main body 100 includes the system controller 50 for controlling theoverall main body 100; a memory 52 that stores constants, variables, andprograms for operating the system controller 50; and a display unit 54that includes an LCD, a loudspeaker, and the like and that indicates theoperating state or a message using characters, images, and sounds inaccordance with a program executed by the system controller 50. Thedisplay unit 54 is provided at a single place or multiple places near anoperation unit(s) of the main body 100 where the display unit 54 isclearly visible. The display unit 54 includes a combination of, forexample, an LCD, a light-emitting diode (LED), a sound generatingelement, and the like. Some of the functions of the display unit 54 areprovided in the optical viewfinder 104.

Among indicators displayed on the display unit 54, for example, thefollowing are displayed on the LCD or the like: a single/continuousphotographing mode indicator, a self-timer indicator, acompression-ratio indicator, an indicator of the number of recordingpixels, an indicator of the number of recorded images, an indicator ofthe remaining number of images that can be captured, a shutter-speedindicator; an aperture-size indicator, an exposure-correction indicator,a flash-correction indicator, an external-strobe-intensity indicator, ared-eye-effect-reduction indicator, a buzzer-setting indicator, anindicator of the remaining battery level, an error indicator, anindicator of information including a number having multiple digits, anindicator of the attached/detached state of the recording media 200 and210, an indicator of the attached/detached state of the lens unit 300,an indicator of a communication interface (I/F) operation, a time/dateindicator, and an indicator of the connection state with an externalcomputer.

Among indicators displayed on the display unit 54, for example, thefollowing are example parameters displayed on the optical viewfinder104: a focus indicator, a ready-to-photograph indicator, a shake-warningindicator, a flash-battery-charge indicator, an indicator of completionof flash battery charge, a shutter-speed indicator, an aperture-sizeindicator, an exposure-correction indicator, and an indicator of arecording-medium writing operation. Among indicators displayed on thedisplay unit 54, for example, an indicator of a recording-medium writingoperation or the like is indicated using the LED or the like. Amongindicators displayed on the display unit 54, a self-timer notificationlamp or the like is indicated using a lamp or the like. The self-timernotification lamp may be commonly used as AF auxiliary light.

The main body 100 includes a non-volatile memory 56, such as anelectrically erasable programmable read-only memory (EEPROM), which canbe electrically erasable and recordable.

The main body 100 includes operation units 60, 62, 64, 66, 68, 69, and70 that are used to enter various operating instructions to the systemcontroller 50 and that include single switches or dials or combinationsthereof. These operation units 60, 62, 64, 66, 68, 69, and 70 aredescribed in more specific detail below.

The operation unit 60 is a mode switch dial used to switch the modeamong various functional photographing modes including an automaticphotographing mode, a programmed photographing mode, a shutter speedpriority AE photographing mode, an aperture priority AE photographingmode, a manual photographing mode, an automatic depth-of-fieldphotographing (auto-depth) mode, a portrait photographing mode, alandscape photographing mode, a macro photographing mode, a sportsphotographing mode, a night-scene photographing mode, and a panoramaphotographing mode.

The operation unit 62 is a shutter switch (hereinafter referred to as a“switch SW1”) that is turned on when a shutter button (not shown) isoperated halfway and gives various instructions to start operationsincluding the AF processing, the AE processing, the AWB processing, andthe EF processing. The operation unit 64 is a shutter switch(hereinafter referred to as a “switch SW2”) that is turned on when theshutter button (not shown) is fully operated and gives an instruction tostart a series of operations including exposure processing of reading asignal from the image pickup device 13 and writing the signal as imagedata in the memory 30 via the A/D converter 16 and the memory controller22, developing processing using the calculation results obtained by theimage processing unit 20 and the memory controller 22, and recordingprocessing of reading the image data from the memory 30, compressing theimage data using the compression/decompression unit 32, and writing theimage data in the recording medium 200 or 210.

The operation unit 66 is a playback switch that gives an instruction tostart a playback operation of reading an image that has been captured ina photographing mode from the memory 30 or from the recording medium 200or 210 and displaying the image using the image display unit 28. Theoperation unit 68 is a live view (LV) start switch used to start a liveview mode. When the live view start switch 68 is turned on, the mirror130 is flipped up, the shutter 12 is opened up, and an optical image isformed on the image pickup device 13, thereby starting a live viewoperation. The operation unit 69 is an AF switch used to temporarilyperform phase-difference AF using the ranging unit 42 in the live viewmode. While the AF switch 69 is being turned on, phase-difference AF isperformed by guiding a light beam incident on the lens 310 through aranging submirror (not shown) and moving the mirror 130 back to aposition so that light can be incident on the ranging unit 42. When theAF switch 69 is turned off, the mirror 130 is flipped up again, and thelive view operation is resumed.

The operation unit 70 includes various buttons, a touch panel, and thelike. More specifically, the operation unit 70 includes a menu button, aset button, a multi-screen-playback new-page button, a flash settingbutton, a single/continuous/self-timer switching button, a menu movementplus (+) button, a menu movement minus (−) button, a playback-imagemovement plus (+) button, a playback image movement minus (−) button, aphotographing-quality selection button, an exposure-correction button, aflash-correction button, an external-strobe light-amount setting button,a date/time setting button, an image-display on/off switch for turningon and off the image display unit 28, a quick-review on/off switch forsetting a quick review function of automatically playing image dataimmediately after the image has been captured, a compression-mode switchfor selecting a compression ratio of Joint Photographic Experts Group(JPEG) compression or for selecting a charge-coupled device (CCD) RAWmode of digitizing a signal obtained by the image pickup device 13 andrecording the digital signal in a recording medium, a playback switchfor setting various functional modes including a playback mode, amulti-screen playback/delete mode, and a personal-computer (PC)connection mode, and an AF-mode setting switch for setting a one-shot AFmode of starting an AF operation when the switch SW1 is turned on and,once focus is achieved, maintaining an in-focus state and a servo AFmode of continuously performing an AF operation while the switch SW1 isturned on. Regarding the functions of the plus and minus buttons,numbers and functions can be more easily selected when a rotational dialswitch is provided.

The main body 100 includes a power switch 72 that switches the powermode of the main body 100 between a power-on mode and a power-off mode.The power switch 72 can also turn on and off power of various auxiliarydevices connected to the main body 100, including the lens unit 300, theexternal strobe, and the recording media 200 and 210.

The main body 100 includes a power controller 80 that includes a batterydetector, a direct current (DC)-to-DC (DC/DC) converter, and a switchunit that changes a block to which electrical connection is established.The power controller 80 detects whether a battery is connected, the typeof the battery, and the remaining power of the battery. Based on thedetection results and an instruction from the system controller 50, thepower controller 80 controls the DC/DC converter and supplies anecessary voltage to each of the components including a recording mediumfor a necessary period of time.

Furthermore, connectors 82, 84 and a power supply 86 including a primarybattery, such as an alkaline battery or a lithium battery, a secondarybattery, such as a NiCd battery or a Li battery, and an AC adapter areprovided. The main body 100 includes interfaces 90 and 94 with recordingmedia including memory cards or hard disks and connectors 92 and 96 thatestablish connections with recording media including memory cards orhard disks.

In the present embodiment, the interfaces and connectors for attachingthe recording media 200 and 210 are provided in pairs. Alternatively,the interfaces and connectors for attaching the recording media 200 and210 may be provided as single elements or plural elements greater thantwo. A combination of interfaces and connectors that conform todifferent standards may be used. As the interfaces and connectors, forexample, Personal Computer Memory Card International Association(PCMCIA) cards or compactflash (registered trademark of SanDiskCorporation) cards may be used.

It is assumed that the interfaces 90 and 94 and the connectors 92 and 96that conform to standards, such as the PCMCIA cards or the compactflashcards, are used. Suppose that various communication cards including alocal area network (LAN) card, a modem card, a universal serial bus(USB) card, Institute of Electrical and Electronic Engineers (IEEE) 1394card, a Small Computer System Interface (SCSI) card, a PersonalHandyphone System (PHS) communication card, and the like are connected.Accordingly, image data and management information accompanying theimage data can be transferred between the main body 100 of the imagepickup apparatus and other computers or peripheral devices includingprinters.

The main body 100 includes the optical viewfinder 104. A light beamincident on the lens 310 is guided by a single-lens reflex method suchthat the light beam passes through the aperture 312, the lens mounts 306and 106, and the mirrors 130 and 132, and an optical image is thusformed on the optical viewfinder 104. Accordingly, an image can becaptured only by using the optical viewfinder 104, without using thelive view function (electronic viewfinder function) of the image displayunit 28. The optical viewfinder 104 includes some of the functions ofthe display unit 54. That is, for example, the optical viewfinder 104displays a focus-state indicator, a shake-warning indicator, aflash-battery-charge indicator, a shutter-speed indicator, anaperture-size indicator, and an exposure-correction indicator.

The main body 100 includes an external strobe device 112 attached to theimage pickup apparatus with an accessory shoe 110.

The main body 100 includes an interface 120 that connects the main body100 to the lens unit 300 in the lens mount 106, and a connector 122 thatelectrically connects the main body 100 to the lens unit 300. Theconnector 122 allows transfer of a control signal, a state signal, and adata signal between the main body 100 and the lens unit 300. Theconnector 122 also has the function of supplying power with variousvoltages. Alternatively, the connector 122 may provide, besideselectrical communication, optical communication, audio communication,and the like.

The mirrors 130 and 132 guide a light beam incident on the lens 310toward the optical viewfinder 104 by using the single-lens reflexmethod. The mirror 132 may either be a quick-return mirror or a halfmirror.

The recording media 200 and 210 are described below. The recordingmedium 200 includes a memory card, a hard disk, or the like. Therecording medium 200 includes a recording portion 202 including asemiconductor memory, a magnetic disk, or the like, an interface 204with the main body 100, and a connector 206 that establishes aconnection with the main body 100. Similarly, the recording medium 210includes a memory card, a hard disk, or the like. The recording medium210 includes a recording portion 212 including a semiconductor memory, amagnetic disk, or the like, an interface 214 with the main body 100, anda connector 216 that establishes a connection with the main body 100.

The lens unit 300 is described below. A light beam incident on the lens310 is guided via the aperture 312, the lens mounts 306 and 106, themirror 130, and the shutter 12, and an optical image of the light beamis formed on the image pickup device 13. The lens mount 306 is used toestablish a mechanical connection between the lens unit 300 and the mainbody 100. The lens mount 306 includes various functions of electricallyconnecting the lens unit 300 to the main body 100.

The lens unit 300 includes an interface 320 that establishes aconnection between the lens unit 300 and the main body 100 in the lensmount 306, and a connector 322 that electrically connects the lens unit300 to the main body 100. The connector 322 allows transfer of a controlsignal, a state signal, and a data signal between the main body 100 andthe lens unit 300. The connector 322 also has the function of receivingor supplying power with various voltages. Alternatively, the connector322 may provide, besides electrical communication, opticalcommunication, audio communication, and the like.

The lens unit 300 includes the aperture controller 340. The aperturecontroller 340 operates in association with the shutter controller 40for controlling the shutter 12 so as to control the aperture 312 basedon photometric information obtained from the photometer 46. The lensunit 300 includes a ranging controller 342 that controls a focusoperation of the image pickup lens 310, a zoom controller 344 thatcontrols a zoom operation of the image pickup lens 310, and a lenssystem controller 350 that controls the overall lens unit 300. The lenssystem controller 350 includes a memory that stores constants,variables, programs, and the like for operations and a non-volatilememory. The non-volatile memory stores identification information of thelens unit 300, such as a serial number unique to the lens unit 300,management information, functional information including an openaperture size, a minimum aperture size, and a focal length, and currentand past setting values.

Differences in photographing operations in the normal mode and the liveview mode are described below. In the normal mode, the image pickupapparatus performs a general single-lens reflex operation. Aphotographing operation in the normal mode is described using theflowchart shown in FIG. 2.

In step S400, the image pickup apparatus is on standby until the switchSW1 is turned on. When the switch SW1 is turned on, the flow proceeds tostep S401. In step S401, the AF processing and the AE processing arestarted using the ranging unit 42 and the photometer 46. The AFprocessing is performed in accordance with a selected AF mode. Forexample, when the on-shot AF mode is selected, the operation is repeateduntil focus is achieved, and, once focus is achieved, the in-focus stateis maintained. In step S402, the state of the switch SW2 is detected.When the switch SW2 is not turned on, the flow returns to step S401, andthe AF processing and the AE processing are repeated.

In contrast, when the switch SW2 is turned on, the flow proceeds to stepS403. In step S403, whether the in-focus state is maintained or not isdetermined. If the in-focus state is not maintained, the flow returns tostep S401. If the in-focus state is determined to be maintained, theflow proceeds to step S404, and an image is captured.

In the normal mode, AF is always performed as preparation for thephotographing operation, as has been described above.

A photographing operation in the live view mode is described using theflowchart shown in FIG. 3.

In step S500, the image pickup apparatus is on standby until the liveview start switch 68 is turned on. When the live view start switch 68 isturned on, the flow proceeds to step S501. In step S501, a live viewoperation is started. That is, as has been described above, the mirror130 is flipped up, the shutter 12 is opened up, and the mode becomes thelive view mode. In the live view mode, a real-time image captured by theimage processing unit 20 is displayed on the image display unit 28. Thatis, a live view display operation is performed. In step S502, the stateof the switch SW1 is detected. When the switch SW1 is turned off, theflow returns to step S501.

In contrast, when the switch SW1 is turned on, the flow proceeds to stepS503. In step S503, AE is performed using the image processing unit 20.Additionally, when the AF processing using the image processing unit 20can be performed, for example, contrast AF can performed, then, contrastAF is performed. However, in the present embodiment, contrast AF is notessential; the AF processing using the image processing unit 20 may notnecessarily be performed.

In step S504, the state of the switch SW2 is detected. When the switchSW2 is turned off, the flow returns to step S503. When the switch SW2 isturned on, the flow proceeds to step S505, and a still image is capturedand recorded. In this still-image photographing operation, since themirror 130 has already been moved up to a position where an opticalimage can be formed on the image pickup device 13, the mirror 130 neednot be driven. Alternatively, the mirror 130 and the shutter 12 mayenter a standby state (the mirror 130 is moved down and the shutter 12is closed), and an image may be captured using the same operation asthat in the normal mode.

In the live view mode, AF serving as preparation for a photographingoperation is not always necessary. This is because of the followingreasons. That is, in the live view mode, an image of an object can beeasily enlarged. Thus, manual focus is suitable for the live view mode.Compared with phase-difference AF performed by the ranging unit 42 inthe normal mode, contrast AF performed using the image processing unit20 in the live view mode has a relatively slow response. When manualfocus is not selected in the live view mode, if contrast AF can beperformed, contrast AF is performed. Otherwise, AF is not performed.

Phase-difference AF performed using the ranging unit 42 in the live viewmode is described using the flowchart of FIG. 4.

In step S600, whether the AF switch 69 is turned on in the live viewmode to give an AF start instruction is determined. When the AF switch69 is turned off, the image pickup apparatus is on standby in this step.Thereafter, when the AF switch 69 is turned on, the flow proceeds tostep S601. In step S601, the mirror 130 and the shutter 12 are broughtback to the standby state, and the live view mode is reset. In stepS602, phase-difference AF is started using the ranging unit 42. The samedescription of the foregoing operation in the normal mode applies tothis AF processing.

In step S603, whether the AF switch 69 is turned off is determined. Whenthe AF switch 69 remains to be turned on, the flow returns to step S602,and phase-difference AF is repeated. Thereafter, when the AF switch 69is turned off, the flow proceeds to step S604. In step S604, the AFprocessing is terminated, and the mirror 130 and the shutter 12 arecontrolled to resume the live view mode.

Accordingly, phase-difference AF using the optical viewfinder can beperformed even in the live view mode.

An operation where the automatic depth-of-field photographing(auto-depth) mode has been selected in the normal mode is describedbelow.

The auto-depth mode is a mode where, among ranging points, all focuspoints where ranging has been successful are adjusted to be closer tothe same depth of field. In the auto-depth mode, a photographingaperture size is also controlled according to the depth of field. Evenwhen there are AF mode settings separate from the photographing mode, ifthe photographing mode is the auto-depth mode, focus adjustment isperformed irrespective of the AF mode settings. For example, even whenthe servo AF mode is selected as the AF mode, a one-shot AF operationgiving priority to the depth of field is performed. FIG. 5 is theflowchart of that operation.

In step S700, the image pickup apparatus is on standby until the switchSW1 is turned on. When the switch SW1 is turned on, the flow proceeds tostep S701. In step S701, ranging is performed, and focus points aredetermined. In step S702, focus adjustment is performed. In step S703, aphotographing aperture size (AV value) for accommodating the determinedfocus points in the depth of field is determined. Thereafter, the flowproceeds to step S704. In step S704, an aperture priority rangingcalculation is performed using the determined aperture size, and ashutter speed (TV value) is calculated.

In step S705, the state of the switch SW2 is detected. When the switchSW2 is turned off, the flow returns to step S704. That is, when theswitch SW2 is not turned on and when the switch SW1 remains to be turnedon, the aperture priority ranging operation is continued using thedetermined aperture size. Every time the photographing luminancechanges, the shutter speed is changed. When the switch SW2 is turned on,the flow proceeds to step S706, and an image is captured using thecalculated aperture size and the shutter speed.

When the mode changes to the live view mode while the auto-depth modehas been selected, the auto-depth mode is switched to a programmed AEmode. This switching operation is described using the flowchart shown inFIG. 6.

In step S800, the image pickup apparatus is on standby until the liveview start switch 68 is turned on. When the live view start switch 68 isturned on, the flow proceeds to step S801. In step S801, as has beendescribed above, the mirror 130 and the shutter 12 are controlled toenter the live view mode. That is, a live view operation is started.

In step S802, the state of the switch SW1 is detected. When the switchSW1 is turned off, the flow returns to step S801, and the live viewoperation is continued. When the switch SW1 is turned on, the flowproceeds to step S803, and the current photographing mode is determined.Since the current photographing mode is the auto-depth mode, the flowproceeds to step S804. In step S804, the photographing mode (auto-depthmode) is changed to the programmed AE mode (P), and the flow proceeds tostep S805. When the current photographing mode is not the auto-depthmode, the flow directly proceeds to step S805.

In step S805, AE is performed using the image processing unit 20. Thatis, if the current photographing mode is the auto-depth mode, program AEthat has been set in step S804 is performed. If the currentphotographing mode is not the auto-depth mode, AE in a mode that hasbeen set using the mode dial switch 60 is performed. Thereafter, theflow proceeds to step S806, and the state of the switch SW2 is detected.When the switch SW2 is turned off, the flow returns to step S803, and asimilar operation is repeated. When the switch SW2 is turned on, theflow proceeds to step S807, and an image is captured using thecalculated aperture size and the calculated shutter speed.

Since photometric calculations are performed irrespective of a focusposition in the programmed AE mode, a live view operation can beperformed irrespective of the focus state in the normal mode.

When an AF operation is performed by accepting that the AF switch 69 hasbeen turned on in the live view mode and resetting the live view mode,AF is not performed in the auto-depth mode, but in a selected AF mode.The operation in that case is described below using the flowchart shownin FIG. 7.

In step S900, the image pickup apparatus is on standby until the liveview start switch 68 is turned on. When the live view start switch 68 isturned on, the flow proceeds to step S901. In step S901, as has beendescribed above, the mirror 130 and the shutter 12 are controlled toenter the live view mode. That is, a live view operation is started.

In step S902, the state of the AF switch 69 is detected. When the AFswitch 69 is turned on, the flow proceeds to step S904, and the mirror130 and the shutter 12 are brought back to the standby state. That is,the live view mode is reset. Thereafter, the flow proceeds to step S905,and the current photographing mode is determined. When the currentphotographing mode is not the auto-depth mode, the flow proceeds to stepS906, and AF in the normal mode is performed in accordance with thephotographing mode and the AF mode setting. In contrast, when thephotographing mode is the auto-depth mode, the flow proceeds to stepS907. In step S907, instead of AF in the auto-depth mode, one-shot AF orservo AF selected by the operation unit 70 as the AF mode is performed.

In step S908, the state of the AF switch 69 is detected. When the AFswitch 69 remains to be turned on, the flow returns to step S905, and asimilar operation is repeated. When the AF switch 69 is turned off, theflow proceeds to step S909. In step S909, the AF processing isterminated, and the mirror 130 and the shutter 12 are controlled toresume the live view mode.

Thereafter, the flow proceeds to step S903, and the state of the switchSW2 is detected. When the switch SW2 is turned off, the flow returns tostep S902, and a similar operation is repeated. When the switch SW2 isturned on, the flow proceeds to step S910, and an image is captured.

When, for example, the servo AF mode is set as the AF mode in the liveview mode, even when the current photographing mode is the auto-depthmode, AF giving priority to the depth of field is not performed.Instead, in step S907, the above-described servo AF processing isperformed. Accordingly, a photographing operation can be performed evenin the live view mode where no AF is performed in the case where thephotographing mode is set to the auto-depth mode.

Generally in the auto-depth mode, besides focus adjustment based on thephotometric result, the photographing aperture size is additionallydetermined. Thus, AF needs to be performed prior to capturing an image.In the live view mode of the present embodiment, since an image can becaptured without operating the AF switch 69, the live view mode is notcompatible with the auto-depth mode. Since the photographing aperturesize may be updated every time AF is performed in the auto-depth mode,when auto-depth AF is performed using the AF switch 69, thephotographing aperture size becomes void at the time the AF switch 69 isturned off and the live view mode is resumed. When a user of the imagepickup apparatus instantly thinks of performing AF in such a state, AFcan be performed in, for example, the servo AF mode so that there are noeffects on the photometric result in the live view mode.

An operation in the case where the one-shot AF mode is selected as theAF mode and evaluation photometry is selected as the photometry mode inthe normal mode is described below using the flowchart shown in FIG. 8.

In step S920, the image pickup apparatus is on standby until the switchSW1 is turned on. When the switch SW1 is turned on, the flow proceeds tostep S921, and ranging is performed. In this case, if an arbitrary pointis selected by the user from among a plurality of ranging points, focusadjustment is performed based on the selected ranging point (S922).Alternatively, if automatic selection has been set, focus adjustment isperformed based on an automatically determined ranging point (S922).

In step S923, evaluation photometry is performed mainly using the focusranging point, and photometric results are calculated. In step S924, thecalculated photometric results (aperture size and shutter speed) arelocked (AE-locked). The photometric results locked in this manner afterfocus is achieved remain constant even when the angle of view is changedwhile maintaining the on-state of the switch SW1 or even when theluminance of the object changes.

When the mode is changed to the live view mode with the foregoingsettings, the operation is switched so that the photometric results willnot be locked after focus is achieved. That is, when an AF operation isperformed using the phase-difference AF method by accepting that the AFswitch 69 has been turned in the live view mode on and resetting thelive view mode, the photometric results are not locked after focus isachieved. This is because of the following reasons. That is, locking ofthe photometric results after focus is achieved is effective based onthe assumption that an image is instantly captured after AF focus isachieved. In the live view mode, AF is only an option (that means thatAF is not essential to capturing an image), and there are no explicitmeans to reset the in-focus state. Therefore, when the photometricresults are locked after the phase-difference AF processing isperformed, the result may be different from that intended by aphotographer. When the photometer 46 and the image processing unit 20have different photometry algorithms, exposure at the time of capturingan image may be different when AF is performed and when no AF isperformed. An operation in such a case is described below using theflowchart of FIG. 9.

In step S950, the image pickup apparatus is on standby until the liveview start switch 68 is turned on. When the live view start switch 68 isturned on, the flow proceeds to step S951. In step S951, as has beendescribed above, the mirror 130 and the shutter 12 are controlled toenter the live view mode. That is, a live view operation is started.

In step S952, the state of the AF switch 69 is detected. When the AFswitch 69 is turned on, the flow proceeds to step S953, and the mirror130 and the shutter 12 are brought back to the standby state. That is,the live view mode is reset. Thereafter, the flow proceeds to step S954,and ranging is performed. In this case, if an arbitrary point isselected by the user from among a plurality of ranging points, theselected point is determined as a ranging point. In step S955, focusadjustment is performed based on the selected ranging point.Alternatively, if automatic selection has been set, focus adjustment isperformed based on an automatically determined ranging point.

In step S956, evaluation photometry is performed by the photometer 46mainly using the focus ranging point, and photometric results arecalculated. Thereafter, the process proceeds to step S957. Photometriccalculations are repeated in step S956 and the photometric results areupdated until the AF switch 69 is detected to be off. That is,photometry is continuously performed in real-time.

When it is detected in step S957 that the AF switch 69 is turned off,the flow proceeds to step S958, and the mirror 130 and the shutter 12are controlled to resume the live view mode.

Thereafter, the flow proceeds to step S959, and the state of the switchSW2 is detected. When the switch SW2 is turned off, the flow returns tostep S952, and a similar operation is repeated. When the switch SW2 isturned on, the flow proceeds to step S960, and an image is captured.

The foregoing description concerns examples where photometry isperformed using the photometer 46 in the case where the AF operationusing the phase-difference AF method is performed. However, during theAF operation performed using the ranging unit 42, AE may or may not beperformed using the photometer 46. Photometric values used to capture animage are obtained by the image processing unit 20 after the live viewmode is resumed. Alternatively, for example, photometry may be performedby the photometer 46, and the photometric values obtained can be used toindicate the photometric values when photometry cannot be performed bythe image processing unit 20. Accordingly, unlike the normalphotographing mode, the user can feel comfortable with operating theimage pickup apparatus when AF is used not as preparation for capturingan image, but as an auxiliary technique. Since the photometric method inthe live view mode can be unified to photometry using the imageprocessing unit 20, the user can use the image pickup apparatus withoutfeeling that there is a difference between the image processing unit 20and the photometer 46.

The image pickup apparatus in the foregoing embodiment has the normalmode using the optical viewfinder 104 and the live view mode using theelectrical viewfinder. The image pickup apparatus has the ranging unit42 for performing an AF operation using the phase-difference AF method,which is enabled when the optical viewfinder 104 is used. In the liveview mode, when a photographing mode of performing photometry inassociation with the AF result is set, the mode is changed to aphotographing mode where photometry is performed not in association withthe AF result.

The photographing mode where photometry is performed in association withthe AF result is the auto-depth mode or a mode where, based on theevaluation photometry results at the focus ranging point, thephotometric values are locked when focus is achieved. The photographingmode where photometry is performed not in association with the AF resultis the programmed AE mode or a mode where photometry is continuouslyperformed in real-time.

As has been described above, in the present embodiment, thephotographing mode where photometry is performed in association with theAF result is switched to the photographing mode where ranging isperformed not in association with the AF result. More specifically, whenthe auto-depth mode is set as the photographing mode, in the live viewmode, the auto-depth mode is switched to the programmed AE mode so thatan operation is performed. Accordingly, user-friendliness that is notbased on an AF operation using the phase-difference AF method can beensured. In other words, generally in the auto-depth mode, no image ispermitted to be captured in an out-of-focus state, and no photographingaperture size is determined. In the live view mode that is not based onan AF operation, no image can be captured without performing AF.However, with the foregoing construction, when the user, who hasselected the auto-depth mode in the normal mode using the opticalviewfinder 104, suddenly switches the mode to the live view mode, it ispossible to overcome a constraint that no image can be directly capturedin the live view mode. In other words, even when an AF operation usingthe phase-difference AF method is performed and then a live viewphotographing operation is performed, photometric results that are notdifferent from those in the case where an image is directly captured inthe live view mode can be ensured.

When a mode where, based on the evaluation photometry results at thefocus ranging point, the photometric values are locked when focus isachieved is selected as the photographing mode, the mode is changed to areal-time photometry mode that is unrelated to a phase-difference AFoperation. Accordingly, user-friendliness can be improved by avoiding,for example, unnecessary AE locking in the case where phase-differenceAF is performed in the live view mode.

That is, an image pickup apparatus that avoids a failure that occurswhen the phase-difference AF and the live view mode are combined can beprovided.

The image pickup apparatus of the present embodiment includes the modedial switch 60 for selecting at least one of the programmed AE mode andthe auto-depth mode and the operation unit 70 for selecting theauto-focus mode. Furthermore, the image pickup apparatus of the presentembodiment includes the AF switch 69 for starting an AF operation usingthe phase-difference AF method in the live view mode. Suppose that theauto-depth mode is set as the photographing mode during the AF operationusing the phase-difference AF method in the live view mode. Even in sucha case, an AF operation using an AF method selected by the operationunit 70 (one-shot AF or servo AF) is performed irrespective of theauto-depth mode.

As has been described above, when the auto-depth mode is set as thephotographing mode, if an AF operation using the phase-difference AFmethod is started in the live view mode, AF is performed in a selectedAF mode irrespective of the auto-depth mode. Accordingly, AF can beperformed without affecting the photometric results obtained in the liveview mode.

That is, when the phase-difference AF and the live view mode arecombined, the following failures occur:

1) In the auto-depth mode, AF is essential to a photographing operation.In contrast, AF is not essential to the live view mode in the presentembodiment (since the AF switch 69 is provided separately from therelease button); and 2) In the auto-depth mode, a photographing aperturesize necessary for the depth of field is calculated only during AF. Incontrast, in the live view mode, AF is terminated and then the live viewmode is resumed. Thus, the live view mode is not compatible with theauto-depth mode.

To overcome the failures, no auto-depth operation is performed in thelive view mode. However, when the user operates the AF switch 69, AF isperformed in accordance with the AF mode that has been set, and focus isachieved.

Accordingly, an image pickup apparatus that can overcome failures thatoccur when the phase-difference AF and the live view mode are combined,that is, failures in AF and the photometric method that occur when theoptical viewfinder and the live view mode can be switched from one tothe other, can be provided.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all modifications and equivalent structures and functions.

This application claims the benefit of Japanese Application No.2007-205370 filed Aug. 7, 2007, which is hereby incorporated byreference herein in its entirety.

1. An image pickup apparatus that can switch between an opticalviewfinder mode for identifying an object using an optical viewfinderand a live view mode for identifying an image of an object using amonitor, the apparatus comprising: an auto-focus unit able to beconfigured in the optical viewfinder mode; and a control unit configuredto switch, in a case where an automatic depth-of-field photographingmode for performing exposure control in association with an auto-focusresult obtained by the auto-focus unit is set, when the opticalviewfinder mode is switched to the live view mode, to a programmedphotographing mode for performing exposure control not in associationwith the auto-focus result,
 2. The image pickup apparatus according toclaim 1, wherein the auto-focus unit is configured to perform auto focusbased on a phase difference.
 3. The image pickup apparatus according toclaim 1, further comprising: a first operation member configured toselect at least one of the programmed photographing mode and theautomatic depth-of-field photographing mode; a second operation memberconfigured to select an auto-focus mode; and an auto-focus controllerconfigured to enable, when the live view mode is switched to the opticalviewfinder mode, even in a case where the automatic depth-of-fieldphotographing mode has been set by the first operation member, theauto-focus unit in the auto-focus mode selected by the second operationmember.
 4. An image pickup apparatus that can switch between an opticalviewfinder mode for identifying an object using an optical viewfinderand a live view mode for identifying an image of an object using amonitor, the apparatus comprising: an auto-focus unit able to beconfigured in the optical viewfinder mode; and a control unit configuredto switch, in a case where a first mode for performing exposure controlin association with an auto-focus result obtained by the auto-focus unitis set, when the optical viewfinder mode is switched to the live viewmode, to a second mode for performing exposure control not inassociation with the auto-focus result, wherein the first mode is a modein which, based on an evaluation photometry result obtained at a focusranging point, a photometric value obtained when focus is achieved islocked, and the second mode is a mode in which photometry iscontinuously performed in real-time.
 5. The image pickup apparatusaccording to claim 4, wherein the auto-focus unit is configured toperform auto focus based on a phase difference.